Search Results

You are looking at 21 - 30 of 29,711 items for :

  • North America x
  • All content x
Clear All
David J. Stensrud

monsoon convection is much more complex with a strong diurnal cycle. To further explore the influence of monsoon convection on the large-scale flow pattern, a case study of the evolution of deep convection and the large-scale flow over a 6-day period during the North American monsoon (NAM) is investigated using a numerical modeling approach. The goal is to examine the upscale response to deep convection in a numerical weather prediction model as determined by comparing model runs with and without the

Full access
Sloan Coats, Benjamin I. Cook, Jason E. Smerdon, and Richard Seager

1. Introduction North America spans three countries, nearly 10 million square miles, and multiple geographical regions with distinct climates, seasonalities, and connections to the wider atmosphere–land–ocean system. While each of the distinct geographic and climatic regions in North America (e.g., the southwest, 32°–40°N, 125°–105°W; versus the central plains, 34°–46°N, 102°–92°W) experience recurrent drought (e.g., Cook et al. 2007 ; McCabe et al. 2004 ; Nigam et al. 2011 ; Schubert et al

Full access
Debjani Ghatak, Gavin Gong, and Allan Frei

Pacific–North American (PNA) pattern, El Niño–Southern Oscillation (ENSO), and the Pacific decadal oscillation (PDO), which suggests that our understanding of snow–climate linkages is incomplete. Studies using North American snow depth (SND, the total depth of old and new snow on the ground) are less common, although the recently released Dyer and Mote (2006 , hereafter DM06) SND data provide the opportunity for research at continental scales. For example, DM06 reported significant negative

Full access
Doug McCollor and Roland Stull

American Ensemble Forecast System (NAEFS; Toth et al. 2006 ). We investigate the quality and value of NAEFS temperature forecasts for 10 cities in western North America. Section 2 describes the forecasts and observations analyzed in the MREF study. Section 3 describes the verification metrics used to evaluate the probabilistic forecasts and discusses the results, and section 4 summarizes the findings and concludes the paper. 2. Methodology a. Ensemble forecasts Raw (unprocessed) temperature

Full access
Enrique R. Vivoni, Hugo A. Gutiérrez-Jurado, Carlos A. Aragón, Luis A. Méndez-Barroso, Alex J. Rinehart, Robert L. Wyckoff, Julio C. Rodríguez, Christopher J. Watts, John D. Bolten, Venkataraman Lakshmi, and Thomas J. Jackson

1. Introduction The North American monsoon (NAM) is the primary climate phenomenon controlling summer precipitation in northwestern Mexico and the southwestern United States (e.g., Douglas et al. 1993 ; Adams and Comrie 1997 ). Convective storms during the monsoon period can account for a large percentage of the total annual precipitation in the region ( Sheppard et al. 2002 ) and lead to significant impacts on the local climate, ecosystem function, and water resources ( Higgins et al. 2003

Full access
Andrew Newman and Richard H. Johnson

temperature anomaly can extend down to near 700 hPa ( Kelly and Mock 1982 ; Whitfield and Lyons 1992 ). TUTT lows in the North American monsoon (NAM) region typically form from the North Atlantic TUTT, or thinning troughs associated with wave breaking over Texas or the western Gulf of Mexico on the downstream side of the upper-level monsoonal ridge ( Thorncroft et al. 1993 ). They are then advected westward south of the monsoonal ridge, as depicted in Fig. 1 for the 12–14 July case observed during the

Full access
Kingtse C. Mo, Li-Chuan Chen, Shraddhanand Shukla, Theodore J. Bohn, and Dennis P. Lettenmaier

system other than precipitation come from the North American Regional Reanalysis (NARR). For surface variables, 2-m temperature and specific humidity and 10-m winds are used. The data have been adjusted to the surface for terrain height ( Cosgrove et al. 2003 ), and biases in the NARR downward solar radiation climatology are corrected using satellite observations from Pinker et al. (2003) . The precipitation data used in the NCEP system are the Climate Prediction Center (CPC)/Office of Hydrologic

Full access
Edmund K. M. Chang

the SRES A1B scenario and found some indications of decreasing frequency along the East Coast and an increase near the West Coast by the end of the twenty-first century. These results are consistent with a projected decrease in eddy kinetic energy (EKE) at 850 hPa over the East Coast and an increase over the western part of the United States found in the same model experiment. Long et al. (2009) examined storm-track projection near the east coast of North America using the Canadian Regional

Full access
Zachary O. Finch and Richard H. Johnson

1. Introduction The North American monsoon (NAM) is an important and complex atmospheric circulation that results in a pronounced increase in rainfall from a dry June to a rainy July over the southwestern United States and northwestern Mexico ( Adams and Comrie 1997 ). Douglas et al. (1993) show that western Mexico receives 60%–70% of annual precipitation during the 3-month period from July to September. The dramatic increase in rainfall is accompanied by a northward shift

Full access
Justin Sheffield, Andrew P. Barrett, Brian Colle, D. Nelun Fernando, Rong Fu, Kerrie L. Geil, Qi Hu, Jim Kinter, Sanjiv Kumar, Baird Langenbrunner, Kelly Lombardo, Lindsey N. Long, Eric Maloney, Annarita Mariotti, Joyce E. Meyerson, Kingtse C. Mo, J. David Neelin, Sumant Nigam, Zaitao Pan, Tong Ren, Alfredo Ruiz-Barradas, Yolande L. Serra, Anji Seth, Jeanne M. Thibeault, Julienne C. Stroeve, Ze Yang, and Lei Yin

1. Introduction This is the first part of a three-part paper on the phase 5 of the Coupled Model Intercomparison Project (CMIP5; Taylor et al. 2012 ) model simulations for North America. The first two papers evaluate the CMIP5 models in their ability to replicate the observed features of North American continental and regional climate and related climate processes for the recent past. This first part evaluates the models in terms of continental and regional climatology, and Sheffield et al

Full access